1. Field of the Invention
The present invention relates to an organic LED (OLED) display apparatus and a manufacturing method thereof, and more particularly relates to a structure for protecting lead wires of an organic light emitting diode display.
2. Description of the Related Art
In OLED display technology, a COF (chip on film) device is commonly used to connect to a glass substrate for display. A driving IC is directly mounted on a circuit film. In other words, COF is a method used to mount a chip of the driving IC onto a flexible printed circuit (FPC) board through flip chip bonding. Therefore, a thinner circuit film substitutes for a conventional thick printed circuit board so that such a display can have reduced weight, thickness, width and size.
COG (chip on glass) is another common technology applicable to the display glass substrate of an OLED display. A driving IC is directly mounted on the glass substrate. The main advantages of COG are as follows: the capacity of the whole package is increased, while the weight is reduced. The display panel is brighter and its manufacturing cost is reduced because fewer components are employed.
However, the lead wires of a conventional OLED display apparatus are not covered by the cover plate, so they are likely to be improperly touched and scratched during succeeding processes. Accordingly, the circuit including the damaged wires could be shorted or even burned out so that the display area of the OLED display apparatus cannot normally display any image. That is, an abnormal light line or an abnormal dark line occurs in the display area. In particular, an OLED display apparatus to which COG technology is applied is likely to be damaged because numerous unprotected and exposed wires or leads can easily be scratched, oxidized or peeled.
FIG. 1 is a top view of a conventional OLED display apparatus. An OLED display apparatus 10 comprises a display area 110 formed on a substrate 100, a plurality of inner leads 121 (cathode) and 122 (anode) and a plurality of outer leads 121′ and 122′. The display area 110 comprises a plurality of anode lines, an organic light-emitting layer and a plurality of cathode lines (not shown) sequentially overlaid on the substrate 100. The display area 110 and the inner leads 121 and 122 are hermetically sealed by an upper cover 150 and the substrate 100. The outer leads 121′ and 122′ provided on the substrate 100 are located outside the upper cover 150, and respectively connected to the inner leads 121 and 122. A driver IC chip 160 mounted on the substrate 100 is located outside the upper cover 150, and electrically connected to outer leads 121′ and 122′ through a plurality of bumps (not shown) so as to control each pixel of the display area 110. Furthermore, a plurality of leads 180 on the substrate 100 are extended under the driver IC chip 160, and similarly are connected to the driver IC chip 160 through a plurality of bumps. The terminal of each lead 180 is connected to a contact 190 that is used to connect to a flexible printed circuit board 170.
FIG. 2 is a top view of the conventional OLED display apparatus in FIG. 1 with protection. The flexible printed circuit board 170 and contacts 190 are connected to each other. An encapsulation material 140 is disposed on the areas of the substrate 100 outside the upper cover 150. Because the outer leads 121′ and 122′ are not protected by any encapsulation material or any film during the succeeding processes after they are formed on the substrate 100, they can be easily scratched, oxidized or peeled. Such defects would exist before the encapsulation material 140 is finally applied to the substrate 100. Metallic leads with higher hardness can substitute the leads 121′ and 122′ to resolve such scratch problem, but the higher resistance of the metallic leads would negatively affect the electrical performance of the OLED display apparatus 10. In another solution, the widths of the outer leads 121′ and 122′ are widened to reduce the risk of complete breakage, but with such method the effective display areas of the OLED display apparatus 10 are more occupied by the leads with increased width. Using leads with widened width cannot meet the requirement of a miniaturized OLED display apparatus. Therefore, the package structure of the conventional OLED display apparatus 10 results in a low manufacturing yield, so the protecting structure of the outer leads 121′ and 122′ should be improved so as to increase the manufacturing yield.